摘要 :
The twin turbine vortex wind mill consists of a pair of multibladed rotors placed at the ends of a hollow cylindrical cage which is specially designed to produce vortex motion. Both the turbines are coupled to a single vertical sh...
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The twin turbine vortex wind mill consists of a pair of multibladed rotors placed at the ends of a hollow cylindrical cage which is specially designed to produce vortex motion. Both the turbines are coupled to a single vertical shaft from which rotary mechanical power could be extracted. On account of the reasonably high rotational speed, this wind mill is suitable for direct generation of electricity.
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In the United States, tornadoes cause significant damage and result in many injuries and deaths. Although the development and use of tornado safe rooms and shelters have helped reduce the human toll associated with these events, t...
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In the United States, tornadoes cause significant damage and result in many injuries and deaths. Although the development and use of tornado safe rooms and shelters have helped reduce the human toll associated with these events, the cost of these structures is often too high for many that could benefit from their use. The development of a residential tornado safe room constructed from commodity wood building products, buildable by a local contractor or do-it-your-self, and adaptable to existing homes could lower the cost of these structures and result in more widespread use. In this study, impact tests were performed on a series of 8-ft by 8-ft wood wall sections according to the standard test criteria of ICC-500. Results indicate that a nailed and glued wall section constructed of three layers of 2 × 8 lumber and sheathed with 23/32-in. CDX plywood can consistently pass the impact test. Included in the test results are the effects of wall construction, sheathing and lumber type, and added adhesive on impact performance.
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Following a preliminary reconnaissance that began on May 24, 2011, the National Institute of Standards and Technology (NIST) announced on June 29, 2011, that it would conduct a technical investigation of the tornado that struck Jo...
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Following a preliminary reconnaissance that began on May 24, 2011, the National Institute of Standards and Technology (NIST) announced on June 29, 2011, that it would conduct a technical investigation of the tornado that struck Joplin, MO, on May 22, 2011. In November 2011, NIST released a draft plan for the study and briefed the National Construction Safety Team (NCST) Advisory Committee on the progress of the investigation in a meeting that was open to the pub-lic. This report summarizes the progress made by the National Institute of Standards and Technology (NIST) in its technical investigation of the tornado that struck Joplin, MO, on May 22, 2011 (re-ferred to after this point as the Joplin tornado).
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On 3 May 1999, a major storm passed through the mid-west, spawning at least 76 tornadoes, and killing more than 50 people. The Oklahoma City, Oklahoma, metropolitan area was the hardest hit, with 43 fatalities, and 10,000 homes de...
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On 3 May 1999, a major storm passed through the mid-west, spawning at least 76 tornadoes, and killing more than 50 people. The Oklahoma City, Oklahoma, metropolitan area was the hardest hit, with 43 fatalities, and 10,000 homes destroyed or severely damaged. The losses due to damage caused by the storm exceeded $1.1 billion. The National Weather Service rated the tornado that struck Oklahoma City as a F5 on the Fujita tornado scale. In the aftermath of the tornadoes, the Building and Fire Research Laboratory Structures Division sent a team to investigate the damage to engineered structures in the Oklahoma City area. The damage reconnaissance included an aerial survey of the largest tornado tracks in central Oklahoma and a two-day ground survey. The ground survey included visits to eight damage sites with twelve damaged engineered structures. This report provides an overview of observed damage to engineered structures, including schools, hotels, and industrial buildings, reports observations on debris accumulation, briefly discusses the tornado rating, and recommends to reduce future losses.
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Oklahoma City (OKC), by virtue of its large areal extent and location near the heart of 'tornado alley,' has earned a reputation over the years as one of the tornado-prone cities in the United States. Each of the 93 tornado listin...
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Oklahoma City (OKC), by virtue of its large areal extent and location near the heart of 'tornado alley,' has earned a reputation over the years as one of the tornado-prone cities in the United States. Each of the 93 tornado listings presented in this report contains the date and time of initial touchdown (note that all times are CST), maximum F-scale rating number of people killed and injured (from the entire event), a dollar estimate of damage (not adjusted for inflation), the data source used, and a narrative describing what is known about the event. Estimated values are in parentheses. Maximum tornado path width and length, if known, are given in brackets at the end of each narrative.
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A computer model was devised to simulate damage patterns caused by a tornado. Results from this model were examined and compared to the actual damage. By manipulating the input values so the output graphs look similar to the actua...
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A computer model was devised to simulate damage patterns caused by a tornado. Results from this model were examined and compared to the actual damage. By manipulating the input values so the output graphs look similar to the actual damage, the magnitude and direction of the ambient wind, and the location of microbursts, could be estimated. The results suggest the tornado was accompanied by ambient winds of at least 20 m/s, and microbursts in all quadrants relative to the tornado motion except the left front quadrant. The results, as well as the distribution of the damage itself, suggest that the intensity of the damage was increased by the presence of microbursts interacting with the tornado.
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Tornado and severe thunderstorm warnings are issued by local offices of the National Weather Service. Routine verification of these warnings is accomplished at the National Severe Storms Forecast Center. The report highlights veri...
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Tornado and severe thunderstorm warnings are issued by local offices of the National Weather Service. Routine verification of these warnings is accomplished at the National Severe Storms Forecast Center. The report highlights verification procedures and summarizes national, regional and local verification results for the year 1987. Stations in the Central and Southern regions again issued most of the warnings and experienced most of the severe local storm events. On a national scale, verification scores showed mixed results. Continued improvement in the False Alarm Ratio and the Critical Success Index are evident with a slight decrease in the Probability of Detection.
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A climatology of annual extreme winds in southern California has been prepared. The climatology includes a description of extreme wind regions, defined on the basis of observed winds and topography. Extreme wind distribution param...
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A climatology of annual extreme winds in southern California has been prepared. The climatology includes a description of extreme wind regions, defined on the basis of observed winds and topography. Extreme wind distribution parameters have been estimated for 46 locations using data obtained from the National Climatic Data Center. Probabilities associated with extreme winds have been estimated for these locations. The results of the analysis are generally consistent with previous estimates of extreme winds in the southern California. Although, in several instances the current estimates are significantly higher than previous estimates. The data examined do not indicate that there has been a significant change in the extreme wind climate of southern California.
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To establish requirements for emergency preparedness plans at facilities licensed by the Office of Nuclear Materials Safety and Safeguards, the Nuclear Regulatory Commission (NRCO) needs to develop source terms (the amount of mate...
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To establish requirements for emergency preparedness plans at facilities licensed by the Office of Nuclear Materials Safety and Safeguards, the Nuclear Regulatory Commission (NRCO) needs to develop source terms (the amount of material made airborne) for accidents. They are used to estimate potential public doses from the events, which will be used to judge whether emergency preparedness plans are needed. Pacific Northwest Laboratory is providing the NRC with source terms by developing accident scenarios for fuel cycle and by-product operations. Several scenarios are developed for each operation, leading to the identification of the maximum release considered for emergency preparedness planning (MREPP) scenario. Fire was the MREPP at oxide fuel fabrication, UF6 production, radiopharmaceutical manufacturing, radiopharmacy, sealed source manufacturing, waste warehousing, and university research and development facilities. Tornadoes were MREPP events for uranium mills and plutonium contaminated facilities, and criticalities were significant at nonoxide fuel fabrication and nuclear research and development facilities. Techniques for adjusting the MREPP release to different facilities are also described.
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